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A bio-inspired compliant robotic fish: Design and experiments
Abstract
This paper studies the modelling, design and fabrication of a bio-inspired fish-like robot propelled by a compliant body. The key to the design is the use of a single motor to actuate the compliant body and to generate thrust. The robot has the same geometrical properties of a subcarangiform swimmer with the same length. The design is based on rigid head and fin linked together with a compliant body. The flexible part is modelled as a non-uniform cantilever beam actuated by a concentrated moment. The dynamics of the compliant body are studied and a relationship between the applied moment and the resulting motion is derived. A prototype that implements the proposed approach is built. Experiments on the prototype are done to identify the model parameters and to validate the theoretical modelling.
... An in-depth description of the compliant robotic fish modelling is given in the article "A Bio-inspired Compliant Robotic Fish: Design and Experiments" [137], which is published in the proceedings of the 2012 IEEE International Conference on Robotics and Automation (Appendix D). A continuation of this study is presented in the article "Modelling of a biologically inspired robotic fish driven by compliant parts" [138] In the first of these articles an added mass is used to define the hydrodynamic forces on the compliant robot's body. ...
... Off-the-shelf pressure sensors are already enough to be used for a real-time control of a rapidly moving vehicle in steady flow as well is in a wake of an object [144]. To prove this point we developed a novel type of fish-robot that incorporated both, fish-like actuation and fish-like sensing [128], [137], [138], [143], [144]. We proposed various control-principles to control the robot with respect to flow using feedback from its artificial lateral line. ...
... To identify the elasticity distribution of fish, we proposed 2 novel approaches: by using Myometry [130] or by applying moment to soft body using gravity [135]. In addition to empirical approach to the tail-design we also contributed to model-based methods by developing an experimental methodology for validating the dynamics models of the biomimetic oscillating fins [137]. ...
... [13] (5) (6) However, the flexible tail is non-uniform (i.e. in Eq.(5), I(x) and ma(x) are not constants), and also finding analytical solutions of Eigen functions for the lateral movement of the non-uniform beam is usually complex. Instead of finding the Eigen functions of a non-uniform beam, [14] used the trial Eigen functions, which are the Eigen functions of a uniform beam. Alvarado and Youcef-Toumi [15] derived a set of complex equations and differential equations so as to discover the eigenvalues and Eigen functions, which is so sophisticated. ...
... R3= 0.0008L, and R4 = 2π/1.1L.Fig. 2 clearly clarifies the geometry of the tail. The second moment of inertia I(x), the area of cross section A(x) and the added mass ma(x) can be denoted and approximated as follows [14,15]: ...
... In order to analyze carefully the walking motion of inchworm, its motion divided into five periods (SeeFig.7 letters a to e).Fig.7 also clarifies that the robot move a distance of 2d during a single pace cycle.Fig. 7. Micro-robot crawling mechanism [14,16] In order to simulate the speed of walking motion of the proposed robot, the displacement of the drivers and the input frequency were considered. Note that the displacement of the actuator in an actual application was demonstrated by d the actuator, and also the displacement of the actuator without payload is demonstrated by d0. ...
... [13] (5) (6) However, the flexible tail is non-uniform (i.e. in Eq.(5), I(x) and ma(x) are not constants), and also finding analytical solutions of Eigen functions for the lateral movement of the non-uniform beam is usually complex. Instead of finding the Eigen functions of a non-uniform beam, [14] used the trial Eigen functions, which are the Eigen functions of a uniform beam. Alvarado and Youcef-Toumi [15] derived a set of complex equations and differential equations so as to discover the eigenvalues and Eigen functions, which is so sophisticated. ...
... R3= 0.0008L, and R4 = 2π/1.1L.Fig. 2 clearly clarifies the geometry of the tail. The second moment of inertia I(x), the area of cross section A(x) and the added mass ma(x) can be denoted and approximated as follows [14,15]: ...
... In order to analyze carefully the walking motion of inchworm, its motion divided into five periods (SeeFig.7 letters a to e).Fig.7 also clarifies that the robot move a distance of 2d during a single pace cycle.Fig. 7. Micro-robot crawling mechanism [14,16] In order to simulate the speed of walking motion of the proposed robot, the displacement of the drivers and the input frequency were considered. Note that the displacement of the actuator in an actual application was demonstrated by d the actuator, and also the displacement of the actuator without payload is demonstrated by d0. ...
In this paper an analysis on a research which is based on fabrication and performance of an underwater robotics including mimicking the propulsion mechanism and physical appearance of both inchworm and fish is done. The proposed micro-robot was used for amphibious application. In order to implement more functions of robot, an insect-inspired robot with four motion attitudes was proposed. Two of actuators (ICPF) are utilized to implement grasping. To create a compact structure with efficient and precise locomotion, and multi‐functionality, a novel micro-robot with eleven ICPF actuators for locomotion and underwater operation are developed, and also two SMA actuators for attitude change are used. The dynamic modeling of flexible tail in the proposed micro-robot is deeply mentioned and it is non-uniform. Finding analytical solutions of Eigen functions for the lateral movement and development of this system can be a prospect approach for further research in the field of underwater micro-robot.
... To imitate the continuum fishtail, the active-segment elastic spine (AES) has also been widely used in robotic fish [25][26][27][28][29][30]. Different from the PES, the elastic deformation of the AES comes into being owing to the active action of the drive mechanism, and the deformation magnitude is controllable. ...
... To imitate carangiform swimming, a robotic fish, whose continuum fishtail contained a section of the polystyrene-chloride-sheet-based active-segment elastic spine and was driven by the L-shape metal bar and wire, was designed by Fujiwara et al [27]. Some similar researches can be found in the literatures [28][29][30]. Although the AES has been widely applied for pursuing continuum fishtail in robotic fish, the researches involving the detailed analysis of the new advantages brought by the AES, and the optimization of the AES are worthy of further exploration. ...
The robotic fish with high propulsion efficiency and good maneuverability achieves underwater fishlike propulsion by commonly adopting the motor to drive the fishtail, causing the significant fluctuations of the motor power due to the uneven swing speed of the fishtail in one swing cycle. Hence, we propose a wire-driven robotic fish with a spring-steel-based active-segment elastic spine. This bionic spine can produce elastic deformation to store energy under the action of the wire driving and motor for responding to the fluctuations of the motor power. Further, we analyze the effects of the energy-storing of the active-segment elastic spine on the smoothness of motor power. Based on the developed Lagrangian dynamic model and cantilever beam model, the power-variance-based nonlinear optimization model for the stiffness of the active-segment elastic spine is established to respond to the sharp fluctuations of motor power during each fishtail swing cycle. Results validate that the energy-storing of the active-segment elastic spine plays a vital role in improving the power fluctuations and maximum frequency of the motor by adjusting its stiffness reasonably, which is beneficial to achieving high propulsion and high speed for robotic fish. Compared with the active-segment rigid spine that is incapable of storing energy, the energy-storing of the active-segment elastic spine is beneficial to increase the maximum frequency of the motor and the average thrust of the fishtail by 0.41 Hz, and 0.06 N, respectively.
... So, in an effort to improve the propulsion and maneuverability of the underwater robot, the effects of the body and tail movements of five different fish species on their propulsion efficiency are investigated. Furthermore, the hull of a fish-like underwater vehicle was modeled and tested by El Daou et al. (2012) to consist of a rigid and dynamic section. Also, natural friction-reducing materials such as shark skins, penguin feathers, dolphin skins, and lotus leaves have been used to enhance the performance of ship hulls in recent years (Yu et al., 2020). ...
According to the conceptual similarities between nature and transportation, the design of systems and vehicles that are inspired by nature and attempt to solve a problem are currently ongoing research topics. The examination of living organisms with biomimicry methodology is essential to the physical and philosophical imitation of nature. Thus, the barriers between natural and engineering sciences are torn down, and the basis for academic and industry references is constructed. Submarines are frequently employed for vital functions and utilize the energy stored in batteries, particularly when in a submerged state. At that time, the service range is defined by stored energy. The need for greater energy capacity to accommodate a longer range will result in an increased overall weight and, therefore, an increase in required propulsion power. Rather than engaging in such a dilemma, the available battery pack can be efficiently utilized by consuming less energy during the same operation. Enhancing the propulsion system or optimizing the body form to minimize resistance might enhance energy efficiency. The purpose is to determine a bio-inspired hull form exposed with less resistance than the DARPA SUBOFF. The body forms such predatory fishes as Barracuda, Dorado, Little Tunny, and Sailfish are compared to the bare SUBOFF.
... Underactuated solutions can enhance the robustness and reliability of a mechanism. El Daou et al. [6] proposed a fish-like subcarangiform robot with a compliant body and a fin connected to it. In [7], a wire-driven active body and a passive, compliant body were used. ...
Biomimetic robotics can help support underwater exploration and monitoring while minimizing ecosystem disturbance. It also has potential applications in sustainable aquafarming management, biodiversity preservation, and animalrobot interaction studies. This study proposes a bio-inspired control strategy for an underactuated robotic fish, which utilizes a single DC motor to drive a mechanism that converts the motor’s oscillating motion into an oscillatory motion of the robotic fishtail through a magnetic coupling and a wire-driven system. The proposed control strategy for the robotic fish is based on central pattern generators (CPGs) and incorporates proprioceptive sensory feedback. The torque exerted on the fishtail is adjusted based on its position, allowing for increased or decreased body speed and steering with different angular speeds and radii of curvature despite the underactuated design. The robotic fish can vary the swimming speed of 0.08 body lengths per second (BL/s) with a related change in the tailbeating frequency up to 2.3 Hz, and it can vary the steering angular speed in the range of 0.08 rad/s with a relative change in the curvature radius of 0.25 m. The controller can adapt to changes in tail structure, weight, or the surrounding environment based on the proprioceptive feedback. Design changes to the modular design can improve speed and steering performances, maintaining the control strategy developed.
... Underactuated mechanisms can provide robust and reliable solutions for robotic systems. El Daou et al. [6] developed a compliant body subcarangiform robot with a linked fin, while [7] used an active wire-driven body and a passive compliant body. Zhong et al. [8] also used a wire-driven mechanism to achieve high-speed swimming, and a two-joint-centred compliant tail was employed for maneuverability in [9]. ...
Bioinspired robotics is a promising technology for minimizing environmental disruption during underwater inspection, exploration, and monitoring. In this research, we propose a control strategy for an underactuated robotic fish that mimics the oscillatory movement of a real fish’s tail using only one DC motor. Our control strategy is bioinspired to Central Pattern Generators (CPGs) and integrates proprioceptive sensory feedback. Specifically, we introduced the angular position of the tail as an input control variable to integrate a feedback into CPG circuits. This makes the controller adaptive to changes in the tail structure, weight, or the environment in which the robotic fish swims, allowing it to change its swimming speed and steering performance. Our robotic fish can swim at a speed between 0.18 and 0.26 body lengths per second (BL/s), with a tail beating frequency between 1.7 and 2.3 Hz. It can also vary its steering angular speed in the range of 0.08 rad/s, with a relative change in the curvature radius of 0.25 m. With modifications to the modular design, we can further improve the speed and steering performance while maintaining the developed control strategy. This research highlights the potential of bioinspired robotics to address pressing environmental challenges while improving solutions efficiency, reliability and reducing development costs.KeywordsBioroboticsBiomimeticsUnderwater roboticsFish robotProprioceptive controlEnvironmental robotics
... Thus, unaided or without special vehicles, most of the underwater world (70% of our world) will remain unexplorable. Underwater robots provide an engineering tool to practical applications in marine and military fields, such as monitoring the environment, harvesting natural resources, undersea operation, pipe inspection, telecoms submersible cable inspection and many more applications (Daou et al., 2012;Mark, 2021 ). This is similar to what the works of Salisu and Shallah (2020) and Martins et al. (2019 aimed to achieve ultimately in terms of robot use for security, human replacement etc on the terra firma. ...
The performance of the steady-turning while swimming, and sharp-turning motion algorithms of a biomimetic underwater robot in the form of a fish is presented in this work. The biological fish modelled is a Mackerel - Scomber scombrus. It’s motion patterns are precalculated and programmed into its firmware as an inflexible algorithm to save power consumption due to continuous motor position recalculations. The robot tail is a six segments plywood panels with vulcanized rubber acting as joints. This tail structure is driven by three remote-control servomotors (Futaba 3003) under the control of microcontroller (PIC18F4520). The algorithm for steady turning is derived steady swimming by introducing offset in the servomotor displacements about the midline of the robot. The algorithm for sharp turning treats the three servomotors as one and turn them simultaneously to left or right and restore them quickly into straight form, which allows the robot to turn at a tight corner. A 54cm turning radius was achieved with the steady turn while swimming. The sharp turn however works but requires several attempts before a proper reorientation was achieved in the desired direction.
... Biomimetic AUV by Guo (2006Guo ( , 2008 had been equipped with advanced control systems such as waypoint tracking and target tracking. The biomimetic approach paved the way for the advancement of robotic fishes that could be used as a platform for performance evaluation (Hu, 2006;Liang et al., 2009;El Daou et al., 2012). A fish-like biomimetic AUV in Marcin et al. (2020) had been developed for Intelligence Surveillance and Reconnaissance (ISR). ...
Efficient low-speed Autonomous Underwater Vehicles (AUV) could adopt a propulsion mechanism with a biomimetic approach of caudal fin propulsion. The developments of the biomimetic AUV have very little attention to the systematic enhancement scheme of the fin performance. Therefore, many unclear relations of the parameters in thrust generation and efficiency of the various types of biomimetic fins. The present study proposes a systematic enhancement scheme of the static and dynamic performances of the biomimetic fins in a low-speed regime. This scheme involves rigid, cupping, and flexible single-joint fins of the acceleration-reaction fin mechanism and a high aspect ratio lunate shape two-joint fin of the lift-based fin mechanism. Average net-force and Thrust-to-Power Ratio evaluated the static performance, while the estimated cruising speed characterized the dynamic performance. The present study shows that the flexible single-joint fin improved the maximum values of the rigid fin performance by three times in average net-force, five times in thrust-to-power ratio, and two and a half times in estimated cruising speed. The two-joint fin enhanced the static and dynamic performances of the flexible fin by three times in average net-force, four times in thrust-to-power ratio, and one and a half times in estimated cruising speed. The present study suggests that flexibility has a role as a thrust vectoring factor. Furthermore, the lift-based mechanism in the two-joint fin provides effective and efficient thrust generation. In the present study, the two-joint fin was the effective and efficient fin propulsion mechanism in a low-speed regime.
... This mechanical response can be used in positioning and force implementing applications that conventional actuators cannot undertake. Some of the advantages of CPAs such as; suitable to be manufactured as mini/micro-sized actuators, operating in solvent or air, large active strains in response to a driving electrical excitation, biocompatibility, and low cost, make them attractive to use in mini/microscale and medical applications such as mechanical stimulation of epithelial cells (Svennersten et al, 2011), a micropump (Fang and Tan, 2010), a bio-inspired compliant robotic fish (El Daou et al., 2012), and a robotic microgripper (Alici and Huynh, 2007). These actuators are named artificial muscles because their working mechanism is similar to that of biological muscles (Bar-Cohen and Zhang, 2008;Carpi et al., 2011;Gaihre et al., 2011). ...
In this paper, a model-free control framework is proposed to control the tip force of a cantilevered trilayer CPA and similar cantilevered smart actuators. The proposed control method eliminates the requirement of modeling the CPAs in controller design for each application, and it is based on the online local estimation of the actuator dynamics. Due to the fact that the controller has few parameters to tune, this control method provides a relatively easy design and implementation process for the CPAs as compared to other model-free controllers. Although it is not vital, in order to optimize the controller performance, a meta-heuristic particle swarm optimization (PSO) algorithm, which utilizes an initial baseline model that approximates the CPAs dynamics, is used. The performance of the optimized controller is investigated in simulation and experimentally. Successful results are obtained with the proposed controller in terms of control performance, robustness, and repeatability as compared with a conventional optimized PI controller.
... By using biomimetic method, there were emerging researches on the implementation of the fin propulsion on man-made underwater technology such as robotic fishes (Refs. [11][12][13][14]). ...
In nature, fishes as the dominant underwater creature use fins to perform underwater locomotion. The caudal fin of fishes, as the main thrust generator, has been studied extensively by many researchers and becomes an inspiration for a highly effective and efficient underwater propulsion. However, the relation of the combination of shape and flexibility of the biomimetic fin to the performance such as thrust and efficiency is still remain unclear. The present research evaluates experimentally the effect of the combination of shape and stiffness variation of biomimetic fins to the fin performance. The shape of the fins were trapezoid in vertical and horizontal cross-section to simplify a natural shape of the posterior body and caudal fin of fish and can be characterized by its taper ratio. The rear-shapes of the fins were varied into truncate, round, fork, and lunate, while the flexibility of the fin were varied based on material and thickness variation from leading edge to the trailing edge. Performance evaluation were performed based on the results of net-thrust, thrust-to-power ratio, and cruising speed. The present research shows that combination of shape and flexibility affect the performance of the fin significantly. Moreover, flexible fins outperforms rigid fin in all performance parameters.
... Also, their low power consumption and simple operation principles make them very attractive as actuators to be used in diverse fields of engineering, robotics, biomedical applications, and biomimetic systems [4][5][6][7][8][9][10]. Some recent applications of conducting polymers in literature include: bio-inspired complaint robotic fish [11], micro-pump [12], and robotic gripper [13]. Although there are many beneficial characteristics of CPAs, they also have some disadvantages such as drift, hysteresis, and degradation in actuation performance caused by solvent evaporation which affect their positioning ability negatively [14]. ...
Conducting polymer actuators (CPAs) are promising candidates for replacing conventional actuators due to their advantageous properties such as low cost, low weight, small actuation voltage and biocompatibility. One of the obstacles for these actuators to become widespread in real world applications is the difficulty of controlling their position or force output as these actuators represent time varying and nonlinear dynamics due to various effects such as synthesis process and conditions, changes in ambient conditions, etc. Linear models are of limited use to design controllers for them since the performance of these controllers may not be sufficient due to model mismatches. Especially, due to their time varying behaviour, a pre-designed controller based on an identified model may show performance deterioration in time. In this study, a model-free control framework is proposed to control the tip displacement of a trilayer conducting polymer actuator with polypyrrole electrodes. The proposed control strategy eliminates the requirement of identification of the dynamics of CPAs for each application and is based on fast derivative estimation of noisy signals. Another advantage of the method is that it is very simple to design and implement. Experimental results are obtained for the model free control method and compared with those of classical PI control.
... A soft-bodied octopus- like arm developed by Laschi et al. demonstrated shortening, elongation and bending [13]. The robot fish FILOSE [14] [15] has a compliant posterior and demonstrated fishlike locomotion. Valdivia y Alvarado and Youcef-Toumi used a soft and compliant body in the design of a robotic fish to mimic the forward swimming kinematics of a real fish [16]. ...
This work presents an autonomous soft-bodied robotic fish that is hydraulically actuated and capable of sustained swimming in three dimensions. The design of a fish-like soft body has been extended to deform under hydraulic instead of pneumatic power. Moreover, a new closed-circuit drive system that uses water as a transmission fluid is used to actuate the soft body. Circulation of water through internal body channels provides control over the fish’s caudal fin propulsion and yaw motion. A new fabrication technique for the soft body is described, which allows for arbitrary internal fluidic channels, enabling a wide-range of continuous body deformations. Furthermore, dynamic diving capabilities are introduced through pectoral fins as dive planes. These innovations enable prolonged fish-like locomotion in three dimensions.
... [1] [4] [5] [10] ...
Mimetic soft underwater robots using PFC are being developed by author's group. High speed and efficiency motions have been realized by the developed robots up to now. However, the robots are with simple shape of flat plate. To realize stream-line shape and embedding electric components inside the robots, it is necessary to prepare interior space inside the robots. For this purpose, this paper proposed basic structure, and the design approach for 3-dimensional fish-like soft underwater robots. And we confirmed the validity for propulsion performance improvement by experiments using developed prototype designed by the proposed method.
... As can be seen inFig.5 the two following legs and legs B, and movement makes the micro-robot Now, if the leading and the counter-clockwise rotation is rotating motion can be simply angle covered in a single cycle5253545556. The displacement of a single different signals is carefully calculated the theoretical walking/crawling theoretical displacements d 0 , without can be seen inFig.7. ...
... As can be seen inFig.5 the two following legs and legs B, and movement makes the micro-robot Now, if the leading and the counter-clockwise rotation is rotating motion can be simply angle covered in a single cycle5253545556. The displacement of a single different signals is carefully calculated the theoretical walking/crawling theoretical displacements d 0 , without can be seen inFig.7. ...
Biomimetic robots have attracted many researches around the world and also living creatures are the best models in biomimetic robotic engineering design. This paper is the combination of three creatures such as tuna, inchworm, gammarus. They are used in order for shortcoming of unrealized multi-functionality. Hence, this paper describes a robot based on the most optimal possible in its field. The dynamic modeling of a flexible tail in the proposed robot are mentioned in detail. The robotic fish is composed of two links connected by an actuated joint; the frontal link is rigid and acts as the robotic fish body, while the rear link serves as the tail. The latter comprises a rigid element connected to a flexible caudal fin, whose underwater vibration is responsible for propulsion. The dynamics of the frontal link are described using Kirchhoff’s equations of motion for rigid bodies in quiescent fluids. The tail vibration is modeled using Euler–Bernoulli beam Theory. Such methods could be a prospect approach for further research in the field of underwater robots.
... As opposed to the traditional mechanical design of using serial chain kinematics for generating undulating motion [23,24], the FILOSE robot uses a compliant tail driven by a single motor. Thrust is generated using vibrations at a resonance frequency mimicking the kinematics of a trout at cruising speeds [25,26]. We have also applied the principle of minimal complexity to the sensor and controller design. ...
This paper describes flow-relative and flow-aided navigation of a biomimetic underwater vehicle using an artificial lateral line for flow sensing. Most of the aquatic animals have flow sensing organs, but there are no man-made analogues to those sensors currently in use on underwater vehicles. Here, we show that artificial lateral line sensing can be used for detecting hydrodynamic regimens and for controlling the robot's motion with respect to the flow. We implement station holding of an underwater vehicle in a steady stream and in the wake of a bluff object. We show that lateral line sensing can provide a speed estimate of an underwater robot thus functioning as a short-term odometry for robot navigation. We also demonstrate navigation with respect to the flow in periodic turbulence and show that controlling the position of the robot in the reduced flow zone in the wake of an object reduces a vehicle's energy consumption.
Researchers have developed numerous artificial fish to mimic the swimming abilities of biological species and understand their biomechanical subaquatic skills. The motivation arises from the interest to gain deeper comprehension of the efficient nature of biological locomotion, which is the result of millions of years of evolution and adaptation. Fin-based biological species developed exceptional swimming abilities and notable performance in highly dynamic and complex subaquatic environments. Therefore, based on research by the scientific community, this mini-review concentrates on discussing the mechanical devices developed to implement the caudal propulsive segments of robotic fish. Caudal mechanisms are of considerable interest because they may be designed to control inertial and gravitational forces, as well as exerting great dynamic range in robotic fish. This manuscript provides a concise review focused on the engineering implementations of caudal mechanisms of anguilliform, subcarangiform, subcarangiform, thunniform and ostraciiform swimming modes.
The integral flexible tail has the potential advantage of lifelike undulating motion. However, due to the complex manufacturing process and difficult modification of structural parameters, its application in robotic fish encounters many challenges. Combining rigid structure and flexible material, this letter proposes a passive flexible fish tail, which can achieve continuous movement and high swimming frequency with simple but effective structure. First, with the full consideration of bending deformation of the spring steels, a dynamic model is established. Next, a passive fitting method is particularly applied to imitate the traveling wave model of the carangiform fish. More importantly, a calculation model, which can be used to acquire the theoretical ranges of the stiffness of spring steels, is derived based on the bending model of the cantilever beam subjected to the concentrated force and moment. Finally, the extensive simulation and experiments validate the effectiveness of the proposed methods, and the designed robotic fish can achieve 0.77 m/s (i.e., 1.12 BL/s) at a swimming frequency of 2.5 Hz. The obtained results can provide a valuable sight for improving the swimming performance of the robotic fish.
Springer International Publishing Switzerland 2016. Thiswork presents an autonomous soft-bodied robotic fish that is hydraulically actuated and capable of sustained swimming in three dimensions. The design of a fish-like soft body has been extended to deform under hydraulic instead of pneumatic power. Moreover, a new closed-circuit drive system that uses water as a transmission fluid is used to actuate the soft body. Circulation of water through internal body channels provides control over the fish’s caudal fin propulsion and yaw motion. A new fabrication technique for the soft body is described, which allows for arbitrary internal fluidic channels, enabling a wide-range of continuous body deformations. Furthermore, dynamic diving capabilities are introduced through pectoral fins as dive planes. These innovations enable prolonged fish-like locomotion in three dimensions.
3-D soft underwater robot using piezoelectric fiber composite is being developed by authors' group. The purpose of this report is to integrate driving systems such as battery, amplifier for piezoelectric fiber composite, microcomputer into the robot, so that the robot can swim in the water without any wiring. First, we design a small driving system with considering the basic requirements. Next, we design and make the prototype based on the structure of real trout in witch built-in driving system can be included. To confirm the basic performance of the prototype, we measure the temperature within the prototype as well as the driving time, and evaluate RSSI (Received Signal Strength Indicator) of wireless module in water. Then, we measure the swimming speed and swimming number to evaluate propulsion performance. As a result, developing the underwater robot with built-in driving system, driving in water, and wireless controlling by external computer have been realized.
A robotic fish is used to test the validity of a simplification made in the context of fish locomotion. With this artificial aquatic swimmer, we verify that the momentum equation results from a simple balance between a thrust and a drag that can be treated independently in the small amplitude regime. The thrust produced by the flexible robot is proportional to A²f², where A and f are the respective tail-beat amplitude and oscillation frequency, irrespective of whether or not f coincides with the resonant frequency of the fish. The drag is proportional to U02, where U0 is the swimming velocity. These three physical quantities set the value of the Strouhal number in this regime. For larger amplitudes, we found that the drag coefficient is not constant but increases quadratically with the fin amplitude. As a consequence, the achieved locomotion velocity decreases, or the Strouhal number increases, as a function of the fin amplitude.
Excellent swimmers, such as tuna, rays, and goldfish, take advantage of their flexible fins, compliant bodies, and swimming bladders to achieve fast, highly maneuverable, and energy-efficient locomotion. Ionic polymer-metal composites (IPMCs) present attractive opportunities for implementation in flexible underwater propulsion systems due to their intrinsic compliancy and underwater actuation capability. IPMCs can also perform as lightweight and compact catalysts for water electrolysis, which can be used to generate gas for buoyancy control. In this chapter, the potential of IPMCs in underwater propulsion is explored, including caudal fin propulsion, pectoral fin propulsion, and buoyancy control. Enabling technologies, including fabrication methods, modeling and control strategies, and design approaches, are developed for creating bio-inspired robots using IPMC as artificial muscle and buoyancy engine. Three types of underwater robots have been developed to evaluate their performance. First, a robotic fish propelled by an IPMC caudal fin is developed to evaluate its caudal fin propulsion. Second, a bio-inspired robotic cownose ray propelled by two IPMC actuated pectoral fins is demonstrated to evaluate its pectoral fin propulsion. Third, a buoyancy control device enabled by IPMC-enhanced electrolysis is developed to explore its buoyancy control performance.
We present a dynamic model of a fish robot with a Non-uniform Flexible Tail (NFT). We investigate the tendencies of the thrust and swimming speed when the input driving moment changes. Based on the proposed dynamic model of the NFT, we derive the thrust estimation, equation of motion, and performance evaluation of a fish robot with a NFT. By defining the optimal stiffness of the NFT in simulation, a fish robot prototype is then designed and fabricated. A series of experiments are performed to verify the proposed model. Experiment results are in good agreement with simulation data. The results show that the thrust and swimming speed of the fish robot are proportional to the amplitude of the driving moment. There are two resonant frequencies (f = 1.4 Hz and 2.2 Hz), the maximum thrust and swimming speed (about 0.7 BL·s−1) are found to be around f = 1.4 Hz. The above results inidicate the proposed model is suitable for predicting the behavior, thrust and swimming speed of a fish robot with a NFT.
As I mentioned in my editorial, soft robotics is a highly collaborative field that relies on successful innovation in very diverse fields. Even the construction of a simple modest device might involve research spanning materials science, control theory, sensing, energy storage, flexible electronics, and a host of breakthroughs in more than one of these fields. Most researchers I know are fully engaged in the advancements within their own field and often lack the opportunity to discuss their projects and their project needs with experts in other disciplines. It is also a challenge for researchers with different backgrounds to communicate effectively and to be aware of new developments in distantly related technologies. A goal of Soft Robotics is to bridge such communication gaps and to share these collaborative discussions with you. To those ends, I have asked each of the following experts to comment on the state of their particular field: Randy H. Ewoldt, Design of Rheologically Complex Materials; Hod Lipson, Evolutionary Robotics; Mirko Kovac, Biomimetic Robots; Mohsen Shahinpoor, Soft Actuators; Nanshu Lu, Flexible Electronics, and Carmel Majidi, Soft Robotics. These insightful perspectives will be followed up by a lively discussion among the participants.
A pneumatically powered, fully untethered mobile soft robot is described. Composites consisting of silicone elastomer, polyaramid fabric, and hollow glass microspheres were used to fabricate a sufficiently large soft robot to carry the miniature air compressors, battery, valves, and controller needed for autonomous operation. Fabrication techniques were developed to mold a 0.65-meter-long soft body with modified Pneu-Net actuators capable of operating at the elevated pressures (up to 138 kPa) required to actuate the legs of the robot and hold payloads of up to 8 kg. The soft robot is safe to interact with during operation, and its silicone body is innately resilient to a variety of adverse environmental conditions including snow, puddles of water, direct (albeit limited) exposure to flames, and the crushing force of being run over by an automobile.
In this work we describe an autonomous soft-bodied robot that is both self-contained and capable of rapid, continuum-body motion. We detail the design, modeling, fabrication, and control of the soft fish, focusing on enabling the robot to perform rapid escape responses. The robot employs a compliant body with embedded actuators emulating the slender anatomical form of a fish. In addition, the robot has a novel fluidic actuation system that drives body motion and has all the subsystems of a traditional robot onboard: power, actuation, processing, and control. At the core of the fish's soft body is an array of fluidic elastomer actuators. We design the fish to emulate escape responses in addition to forward swimming because such maneuvers require rapid body accelerations and continuum-body motion. These maneuvers showcase the performance capabilities of this self-contained robot. The kinematics and controllability of the robot during simulated escape response maneuvers are analyzed and compared with studies on biological fish. We show that during escape responses, the soft-bodied robot has similar input-output relationships to those observed in biological fish. The major implication of this work is that we show soft robots can be both self-contained and capable of rapid body motion.
Inspired by biological swimmers such as fish, a robot composed of a rigid head, a compliant body and a rigid caudal fin was built. It has the geometrical properties of a subcarangiform swimmer of the same size. The head houses a servo-motor which actuates the compliant body and the caudal fin. It achieves this by applying a concentrated moment on a point near the compliant body base. In this paper, the dynamics of the compliant body driving the robotic fish is modelled and experimentally validated. Lighthill’s elongated body theory is used to define the hydrodynamic forces on the compliant part and Rayleigh proportional damping is used to model damping. Based on the assumed modes method, an energetic approach is used to write the equations of motion of the compliant body and to compute the relationship between the applied moment and the resulting lateral deflections. Experiments on the compliant body were carried out to validate the model predictions. The results showed that a good match was achieved between the measured and predicted deformations. A discussion of the swimming motions between the real fish and the robot is presented.
In this paper, a non-uniform flexible tail of a fish robot was presented and the dynamic model was developed. In this model, the non-uniform flexible tail was modeled by a rotary slender beam. The hydrodynamics forces, including the reactive force and resistive force, were analyzed in order to derive the governing equation. This equation is a fourth-order in space and second-order in time Partial Differential Equation (PDE) of the lateral movement function. The coefficients of this PDE were not constants because of the non-uniform beams, so they were approximated by exponential functions in order to obtain an analytical solution. This solution describes the lateral movement of the flexible tail as a function of material, geometrical and actuator properties. Experiments were then carried out and compared to simulations. It was proved that the proposed model is suitable for predicting the real behavior of fish robots.
This paper presents the dynamic modeling of a flexible tail for a robotic fish. For this purpose firstly, the flexible tail was simplified as a slewing beam actuated by a driving moment. The governing equation of the flexible tail was derived by using the Euler-Bernoulli theory. In this equation, the resistive forces were estimated as a term analogous to viscous damping. Then, the modal analysis method was applied in order to derive an analytical solution of the governing equation, by which the relationship between the driving moment and the lateral movement of the flexible tail was described. Finally, simulations and experiments were carried out and the results were compared to verify the accuracy of the dynamic model. It was proved that the dynamic model of a fish robot with a flexible tail fin well explains the real behavior of robotic fish in underwater environment.
We investigate the problem of a heaving and pitching hydrofoil in an inflow that consists of a uniform velocity field and a staggered array of vortices. The foil can exploit the energy in such a Karman vortex street for efficient propulsion of animals or submarines. Through a two-dimensional inviscid analysis, me find that the phase between foil motion and the arrival of inflow vortices is a critical parameter. Everything else being equal, the highest efficiency is seen when this phase is such that the foil moves in close proximity to the oncoming vortices. Different modes of vortex interaction in the wake results from a variation in this phase, and we show that the how downstream of the foil is related to the foil input power.
The aim of this work is to investigate alternative designs for machines intended for biomimetic locomotion in liquid environments. For this, structural compliance instead of discrete assemblies is used to achieve desired mechanism kinematics. We propose two models that describe the dynamics of special compliant mechanisms that can be used to achieve biomimetic locomotion in liquid environments. In addition, we describe the use of analytical solutions for mechanism design. Prototypes that implement the proposed compliant mechanisms are presented and their performance is measured by comparing their kinematic behavior and ultimate locomotion performance with the ones of real fish. This study shows that simpler, more robust mechanisms, as the ones described in this paper, can display comparable performance to existing designs.
Presently, there is a need for devices capable of autonomous locomotion in liquid environments. Humanitarian, industrial and defense applications are numerous and include examples such as search and rescue missions, ocean exploration, and de-mining operations. Due to the nature of the environments involved, the required devices must overcome several challenges. The main challenges are related to hardware performance in terms of propulsion efficiency, mechanical robustness, maneuverability, adaptability, stealth and autonomy. Current traditional approaches that use propeller driven devices have limited success in addressing these challenges. As a result devices that mimic fish-like swimming techniques have emerged as a promising alternative that can provide additional maneuvering features and the promise of improved performance. However, the inherent problems of current biomimetic devices have been identified as: (i) mechanical complexity due to the use of discrete and rigid components, and (ii) lack of a systematic design approach. These problems limit the practical implementation of biomimetic techniques in real mission environments. This thesis presents an alternative approach for implementing biomimetic fish-like swimming techniques by exploiting natural dynamics of compliant bodies.
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2000. Includes bibliographical references (p. 75-76). by John Muir Kumph. S.M.
We have developed an experimental procedure in which the in situ locomotor muscles of dead fishes can be electrically stimulated to generate swimming motions. This procedure gives the experimenter control of muscle activation and the mechanical properties of the body. Using pumpkinseed sunfish, Lepomis gibbosus, we investigated the mechanics of undulatory swimming by comparing the swimming kinematics of live sunfish with the kinematics of dead sunfish made to swim using electrical stimulation. In electrically stimulated sunfish, undulatory waves can be produced by alternating leftright contractions of either all the axial muscle or just the precaudal axial muscle. As judged by changes in swimming speed, most of the locomotor power is generated precaudally and transmitted to the caudal fin by way of the skin and axial skeleton. The form of the traveling undulatory wave as measured by tail-beat amplitude, propulsive wavelength and maximal caudal curvature can be modulated by experimental control of the body's passive stiffness, which is a property of the skin, connective tissue and axial skeleton.
A manipulator, or 'robot', consists of a series of bodies (links) connected by joints to form a spatial mechanism. Usually the links are connected serially to form an open chain. The joints are either revolute (rotary) or prismatic (telescopic), various combinations of the two giving a wide va riety of possible configurations. Motive power is provided by pneumatic, hydraulic or electrical actuation of the joints. The robot arm is distinguished from other active spatial mechanisms by its reprogrammability. Therefore, the controller is integral to any de scription of the arm. In contrast with many other controlled processes (e. g. batch reactors), it is possible to model the dynamics of a ma nipulator very accurately. Unfortunately, for practical arm designs, the resulting models are complex and a considerable amount of research ef fort has gone into improving their numerical efficiency with a view to real time solution [32,41,51,61,77,87,91]. In recent years, improvements in electric motor technology coupled with new designs, such as direct-drive arms, have led to a rapid increase in the speed and load-carrying capabilities of manipulators. However, this has meant that the flexibility of the nominally rigid links has become increasingly significant. Present generation manipulators are limited to a load-carrying capacity of typically 5-10% of their own weight by the requirement of rigidity. For example, the Cincinatti-Milicron T3R3 robot weighs more than 1800 kg but has a maximum payload capacity of 23 kg.
Contents. 1. Introduction. 2. Mathematical Preliminaries. 3. Flexible Robot Dynamic Modeling. 4. System Identification. 5. Input Shaping for Path Planning. 6. Linear Feedback Control. 7. Nonlinear Systems and Sliding Mode Control. 8. Adaptive Sliding Mode Control. Appendix A: VF02AD Optimization. Appendix B: MATLAB%% Optimization. Appendix C: Hardware & Software Support.
The principle aim of the work described in this book is to investigate the implications of flexible manipulator dynamics for closed-loop control design and the use of dynamic models to develop efficient and robust control schemes for flexible manipulators. After reviewing the current research in flexible arm dynamics and control the following subobjectives are identified: 1. To demonstrate experimentally the application of modal modelling techniques to flexible manipulators. A single-link flexible arm was designed as a practical testbed and good agreement was found between the arm’s observed behaviour and that predicted by the modal model. 2. To demonstrate that, while the modal model theoretically has an infinite number of modes, it is possible to achieve good control based on a reduced-order model. This is in contrast with the theoretical work of other researchers notably Truckenbrodt and Balas. 3. To investigate the effects of loading and configuration changes on fixed-parameter control schemes. Although this is an area that has hitherto received little attention, it is central to the control of manipulators which, in performing their programmed tasks, will invariably undergo changes in orientation and load. The single-link arm was used to investigate the effect of changing tip mass on performance and a general modal model for a planar two-link manipulator was developed to determine the effects of configuration changes. 4. To develop a practical control scheme which satisfies the restrictions of real-time implementation. Although fixed-parameter controllers were found to be capable of giving good control for small loading and configuration changes around the nominal design conditions a general deterioration in closed-loop performance was noted. In view of this, techniques for adjusting the controller gains to maintain the performance needed to be developed. Ideally, the control design procedure should be repeated using the updated model of the arm. However, this ignores the practical considerations of on-line implementation. Even reduced-order models of flexible manipulators contain a large number of states, and typical operations used in the control design, such as matrix inversion, are computationally intensive. More efficient methods based on perturbation techniques were developed and demonstrated on both the single-link arm and two-link model.
When a fish swims in water, muscle contraction, controlled by the nervous system, interacts with the body tissues and th surrounding fluid to yield the observed movement pattern of the body. A continuous dynamic beam model describing the bendin moment balance on the body for such an interaction during swimming has been established. In the model a linear visco–elasti assumption is made for the passive behaviour of internal tissues, skin and backbone, and the unsteady fluid force acting o the swimming body is calculated by the 3D waving plate theory. The body bending moment distribution due to the various components in isolation and acting together, is analysed. The analysis is based on the saithe (Pollachius virens), a carangiform swimmer. The fluid reaction needs a bending moment of increasing amplitude towards the tail and near–standin wave behaviour on the rear–half of the body. The inertial movement of the fish results from a wave of bending moment wit increasing amplitude along the body and a higher propagation speed than that of body bending. In particular, the fluid reaction mainly designed for propulsion, can provide a considerable force to balance the local momentum change of the body and thereb reduce the power required from the muscle. The wave of passive visco–elastic bending moment, with an amplitude distributio peaking a little before the mid–point of the fish, travels with a speed close to that of body bending. The calculated muscl bending moment from the whole dynamic system has a wave speed almost the same as that observed for EMG–onset and a startin instant close to that of muscle activation, suggesting a consistent matching between the muscle activation pattern and th dynamic response of the system in steady swimming. A faster wave of muscle activation, with a variable phase relation betwee the strain and activation cycle, appears to be designed to fit the fluid reaction and, to a lesser extent, the body inertia and is limited by the passive internal tissues. Higher active stress is required from caudal muscle, as predicted from experimenta studies on fish muscle. In general, the active force development by muscle does not coincide with the propulsive force generatio on the tail. The stiffer backbone may play a role in transmitting force and deformation to maintain and adjust the movemen of the body and tail in water.
Effective control laws for mechanical systems are best designed by professionals who understand both the basic mechanics of the system under consideration and the control methodology being used to design the control law. This textbook is the first to blend two traditional disciplines: engineering mechanics and control engineering. Beginning with theory, the authors proceed through computation to laboratory experiment and present actual case studies to illustrate practical aerospace applications. Intended for first-year graduate students in engineering and applied science, this book will help the next generation of structural dynamists and control engineers gain broad competence in mechanics and control. A software package, SDCMO: Structural Dynamics and Control MATLAB Operators, complements this important new teaching tool. A 100-page solutions manual is available for professors.
This paper firstly presents a short review on the current research of robotic fish. The construction of a simulation environment for robotic fish is then presented. The experiment results show that the simulator is a convenient way to develop and test the motion control algorithm for a robotic fish. Furthermore, a parameter optimising method for fish's travelling wave approximation is proposed. A special error function is selected depending on the hydrodynamics theory of fish. n nature, fish has astonishing swimming ability after thousands years evolution. It is well known that the tuna swims with high speed and high efficiency, the pike accelerates in a flash and the eel could swims skillfully into narrow holes. Such astonishing swimming ability inspires the researchers to improve the performance of aquatic man-made systems. An example application is robotic fish. Instead of the conventional rotary propeller used in ship or underwater vehicles, the undulation movement like fish provides the main energy of the robotic fish. The observation on the real fish shows that this kind of propulsion is more noiseless, effective, and manoeuvrable than the propeller-based propulsion. So, the robotic fish could be used in many marine and military fields such as exploring the fish behaviours, detecting the leakage of oil pipeline, robotics education, mine countermeasures, etc.
Vorticity control is a new paradigm in propulsion hydrodynamics. In this thesis, we study fish-like propulsion strategies as concepts in vorticity control. We investigated the flow around a swimming fish, the propulsive properties of a rigid oscillating foil and the interaction of an oscillating foil with upstream vorticity. Digital particle image velocimetry (DPIV) was used to make quantitative multipoint measurements of the unsteady flow fields. Fish are the prime example of vorticity control: they propel and maneuver by manipulating vorticity formed along their body which interacts with the tail. We measured the flow around a small fish while swimming straight and while turning. For straight steady swimming, the flow in the horizontal plane closely resembles two-dimensional swimming plate theory. Next, we investigated the propulsive properties of a rigid flapping foil harmonically oscillated in heave and pitch with large amplitude as a function of frequency and angle of attack. Dynamic stall occurs for most thrust producing cases and its formation and evolution are largely influenced by the kinematics of the foil. Finally, we studied the tandem combination of a bluff body and a flapping foil as a simple type of vorticity control to clarify vortex-foil interaction processes. Our results indicate that vorticity control of this type may lead to improved efficiency and reduced wake signature.
The succession of hypotheses on the role of myotomal muscle in the generation of swimming movements is described and the conventional concept of ‘waves of contraction’ is shown to be based on a number of misinterpretations.
The form of undulatory movements in vertebrate swimmers is characterized by the properties of the sinusoidal oscillation of parts of the body about the axis of progression. An important variable is the relative amplitude of the lateral oscillation of the head end, which can be large in some animals though usually small in most adult aquatic vertebrates.
Cinematographic records of swimming animals are examined to determine the forces involved in the generation of waves of bending. A simplified analysis suggests that undulation can be produced by alternation of tension development from side to side without ‘waves of contraction’ passing down the body.
Model systems which are able to flex from side to side are considered and two types distinguished ‐ the ‘resistance‐dominated’ which propagates waves of bending from centre to extremities, and the ‘stiffness‐dominated’ which does not. The type to which a model belongs is determined by the interrelationship of its stiffness and resistance, and the power with which it flexes.
A model homogeneous in its properties along its length cannot generate longitudinal movement by flexing from side to side. Some degree of unevenness from one end to the other is required for propulsion.
Observations of the movements of an ‘ostraciiform model’ are shown to discount previous theories of the hydromechanics of swimming by the oscillation of a stiff tail about a single pivot. A new interpretation is provided.
The majority of vertebrate swimmers behave like ‘hybrid oscillators’ which flex from side to side, ‘resistance‐dominated’ posteriorly and ‘stiffness‐dominated’ anteriorly.
The origin of the ‘waves of contraction’ suggested by electromyograms of swimming animals is traced to the requirement for a tail of variable stiffness for variable frequency of oscillation and to the need to reduce lateral oscillation of the head. Delayed contraction posteriorly and early contraction anteriorly contribute to these functions.
The ability of amphioxus to swim backwards and the inability of most vertebrates to do so is related to their structural organization in the form of ‘hybrid oscillators’.
Electromyograms are examined in the light of these mechanical models. A developmental sequence is described for the newt which illustrates the organization of the muscular control of swimming movements and may throw light upon the development of the neural mechanism.
A simple and easy-to-implement algorithm to identify a generalized proportional viscous damping matrix is developed in this work. The chief advantage of the proposed technique is that only a single drive-point frequency response function (FRF) measurement is needed. Such FRFs are routinely measured using the standard techniques of an experi-mental modal analysis, such as impulse test. The practical utility of the proposed iden-tification scheme is illustrated on three representative structures: (1) a free-free beam in flexural vibration, (2) a quasiperiodic three-cantilever structure made by inserting slots in a plate in out-of-plane flexural vibration, and (3) a point-coupled-beam system. The finite element method is used to obtain the mass and stiffness matrices for each system, and the damping matrix is fitted to a measured variation of the damping (modal damping factors) with the natural frequency of vibration. The fitted viscous damping matrix does accommodate for any smooth variation of damping with frequency, as opposed to the conventional proportional damping matrix. It is concluded that a more generalized vis-cous damping matrix, allowing for a smooth variation of damping as a function of frequency, can be accommodated within the framework of standard finite element mod-eling and vibration analysis of linear systems.
This paper presents a 3D simulator used for studying the motion control and autonomous navigation of robotic fish. The simulator’s
system structure and computation flow are presented. Simplified kinematics and hydrodynamics models for a virtual robotic
fish are proposed. Many other object models are created for water, obstacles, sonar sensors and a swimming pool. Experimental
results show that the simulator provides a realistic and convenient way to develop autonomous navigation algorithms for robotic
fish.
This paper presents a novel mechatronics design for a 3D swimming robotic fish, namely MT1 (Mechanical Tail) robotic fish. It has a novel tail structure which uses only one motor to generate fish-like swimming motion using C-bends tail shapes. This design enables MT1 to become the first small size robotic fish (<0.5m in length) and be able to dive over 3 meters deep in water. An effective control method with only 5 parameters is proposed to control its 3D swimming behaviours. Experimental results are presented to show the feasibility and good performance of the proposed control algorithms.
In this paper, a physics-based model is proposed for a biomimetic robotic fish propelled by an ionic polymer-metal composite (IPMC) actuator. Inspired by the biological fin structure, a passive plastic fin is further attached to the IPMC beam. The model incorporates both IPMC actuation dynamics and the hydrodynamics, and predicts the steady-state cruising speed of the robot under a given periodic actuation voltage. The interactions between the plastic fin and the IPMC actuator are also captured in the model. Experimental results have shown that the proposed model is able to predict the motion of robotic fish for different tail dimensions. Since most of the model parameters are expressed in terms of fundamental physical properties and geometric dimensions, the model is expected to be instrumental in optimal design of the robotic fish.
In nature, fish has astonishing swimming ability after thousands years of evolution. To realise fish-like swimming behaviours by a robotic system poses tremendous challenges, especially for the C-shape turning (CST). This requires fully understanding of fish biomechanics and the way to mimic it. Based on observations of fish swimming, this paper presents a new kinematics model to mimic the CST behaviour in a robotic fish with a 4-DOF (degrees of freedom) tail. The simulated and the real experiments are conducted to show the theoretic feasibility. Both behaviour analyses and hydrodynamics features between the robotic fish and the real fish are presented to show the performance.
IT HAS been accepted generally that the waves of bending observed in
swimming vertebrates are produced by contraction on the concave side of
each bend of the body at any point within the cycle of
movement1-3. ``Waves of contraction'' are imagined to pass
down the serial mytomes with the velocity of the propagated bends.
Another concept, designed primarily to explain snake
locomotion4, differs by a 90° shift in the timing of
contraction on the bending wave, accounting for propulsion but resulting
in illogical analysis of fish movement5. The former
interpretation gives no explanation of the source of locomotory thrust,
assuming falsely that the muscular activity required for a given body
position is similar whether the position is held or passed through in
locomotion. The dominant responsibility of locomotory activity is the
propagation rather than the formation of bends, but how is propagation
achieved against external resistance? Relevant electromyography of
spinal dogfish6,7 has not been related to this mechanical
problem. I present here a preliminary report of electromyographic
studies of developmental stages of the palmate newt, Triturus helveticus
(Razoumowsky), and adult tench, Tinca tinca L., which show that
undulatory propulsion in some animals does not involve waves of
contraction and that the ``waves'' recorded in others function in
reducing lateral oscillation anteriorly and adapting tail flexibility to
different swimming speeds.
This paper presents a 3D simulator used for studying the motion control and autonomous navigation of a robotic fish. The simplified kinematics and hydrodynamics models are created for the simulator, including many other object models such as water, obstacles, sonar sensors and a swimming pool. The experimental results show that the use of this simulator is a realistic and convenient way to develop autonomous navigation algorithms for robotic fishes.
Flexible Robot Dynamics and Controls " , International Federation for Systems Research
- R D Iii Robinett
- C Dohrmann
- G R Eisler
- J Feddema
- G G Parker
- D G Wilson
- D Stokes
R.D. III Robinett, C. Dohrmann, G.R. Eisler, J. Feddema, G.G. Parker, D.G. Wilson, and D. Stokes, " Flexible Robot Dynamics and Controls ", International Federation for Systems Research, International Series on Systems Science and Engineering, Vol. 19, Kluwer, Dordrecht, 2002.